Fungi which infest seed are frequently capable of inflicting severe crop losses throughout the world. This is especially true of Helminthosporium species, such as H. oryzae, H. teres, H. sativum, H. gramineum and H. avenae, which attack most of the more important cereals and grasses including barley, wheat, rye, oats, sorghum, millet, rice, corn and cultivated grasses. Helminthosporium species produce various symptoms. For example, in rice, germination may be prevented or seedlings killed or distorted by dead leaf spots. In barley, lesions occur on the sheaths that cover the young shoots, and plants may be killed by root or basal rot. Immense numbers of spores may be produced on older plants which contaminate or infect developing seeds and serve to carry the fungus directly from one year's crop to the next.
In the past, compounds containing mercury have been applied to various seeds to disinfest them of fungi such as Helminthosporium. Recently, however, difficulties have been encountered with the use of mercury and it has been banned from the market, thus a replacement is needed.